Perhaps Harry would have a unique understanding of magic. House elves have their own brand of magic that is different from what wizards learn at Hogwarts. He might combine these two types of magic in unexpected ways, like using house - elf magic for household chores and wizard magic for more complex spells, but in a way that is more efficient than traditional wizarding methods.
One idea could be that Harry grows up with a very different set of values. House elves are known for their loyalty and hard work. So, Harry might be more in tune with serving others selflessly. For example, he could be more eager to help his classmates with their problems without expecting anything in return.
One idea could be a story about a house - elf who discovers a hidden magic within themselves that allows them to break free from the traditional bonds of servitude. They could then go on a journey to find other house - elves and teach them this new magic.
Perhaps Harry, being raised by house elves, has a very different view of the wizarding world's social hierarchy. He may see the unfair treatment of house elves as completely unacceptable from a young age and strive to change it. This could lead to him getting into conflicts with some of the more traditional pure - blood families who rely on house - elf labor.
One plot idea could be that the house - elf imparts unique magical knowledge to Harry that he doesn't get at Hogwarts. For example, teaching him ancient spells passed down in the house - elf community. Another could be that the house - elf protects Harry from threats in a very different way than Dumbledore or his friends. Maybe the house - elf uses its own brand of magic, which is more instinctive and less rule - bound.
One possible plotline could be that the Potter elves teach Harry unique magic that is different from what he would learn at Hogwarts. For example, they might show him ancient elf magic that gives him an edge in dealing with dark forces. Another could be that the elves raise Harry with a strong sense of family and loyalty, which makes him more empathetic towards those who are often overlooked in the wizarding world, like house - elves themselves.
In some 'Harry Potter raised by elves fanfiction', a possible plotline is that the elves teach Harry their language and ancient magic. This gives him an edge in his later adventures as he can access magic that other wizards don't know. Also, the elves' strong sense of loyalty and family could influence Harry, making him more empathetic towards those who are often overlooked in the wizarding society, like the house - elves themselves.
One interesting concept is the idea of house - elves gaining more rights. In some fanfictions, they form unions or rebel against the traditional wizarding hierarchy. Another concept could be a house - elf having magical abilities that are far beyond what is shown in the original books, like being able to perform extremely powerful spells. Also, there are fanfictions where a house - elf forms a deep friendship with a wizard or witch outside of their serving duties, which is quite different from the normal master - servant relationship in the original story.
It could be really interesting. Maybe Harry would grow up with a different set of values. House elves are very loyal and hardworking, so Harry might be more attuned to their way of life. He could be more humble and less likely to seek the spotlight like he did in the original story.
One interesting plot could be how Harry's magical abilities are perceived in a world of nations. Maybe he uses his magic to solve international disputes. Another idea is that different nations try to influence his upbringing, each adding their own cultural and magical elements to his training.
One idea could be that Harry grows up with cat - like reflexes and stealth. He might be able to move around Hogwarts unnoticed more easily, like a cat prowling in the shadows.
In the fanfiction, it could be interesting if Harry uses his magic to protect the other orphans from bullies. He might not fully understand his powers yet, but his instincts kick in. And then when he finally gets his Hogwarts letter, the other orphans are both sad to see him go but also excited for him, and he has to figure out how to leave the only home he's known while also being eager to enter the wizarding world.